Synthesis of Non-Natural Heteroaminopolysaccharides by α-Glucan Phosphorylase-Catalyzed Enzymatic Copolymerization: α(1→4)-Linked Glucosaminoglucans

Thermostable α-glucan phosphorylase-catalyzed enzymatic copolymerization of α-d-glucose 1-phosphate (Glc-1-P) with its analogue monomer, α-d-glucosamine 1-phosphate (GlcN-1-P), from a maltotriose primer was performed to produce non-natural heteroaminopolysaccharides composed of Glc/GlcN units, that is, α(1→4)-linked glucosaminoglucans. The GlcN units in the products were further converted to N-acetyl-d-glucosamine (GlcNAc) units by N-acetylation. The structures of the products were evaluated by the MALDI-TOF MS, (1)H NMR, and (1)H-(1)H COSY NMR measurements, which were completely different from those of the natural glycosaminoglycans. The degrees of polymerization and Glc/GlcN compositional ratios of the products were relatively dependent on the Glc-1-P/Glc-1-P/Glc3 feed ratios. The noncrystalline natures of the present materials were supported by the X-ray diffraction measurement.